It seems like nobody involved in this movie had a firm idea on how funny it should be, where the humor would come from, what kind of character Wilder should play, or how to develop the characters' relationships, and so even tho it's great seeing Wilder and Ford at the height of their powers, the movie itself is a total dud.
I liked a lot of the dry humor and some of the poetic language, but I found the book overall to be solipsistic and dull.